A chemical reaction is a process that leads to the transformation of one set of chemical substances to another substance. Classically, chemical reactions encompass changes that strictly involve the motion of electron in the forming and breaking of chemical bonds. The concept of electron transfer can easily explain in the redox reactions in the case of ionic substances. However, for covalent compounds we use a new term oxidation number to explain oxidation and reduction or redox reactions. Redox reactions are the chemical reactions which involve both oxidation as well as reduction simultaneously. ln fact, oxidation and reduction go hand in hand.